The invention relates to an adjustment device for a clutch with a load moment lock.
An adjustment device with a load moment lock is known from DE 41 20 617 C2 through which torque on the drive side is transferred in both directions to an output element whilst torque on the output side is blocked in both directions by the load moment lock and the force is directed into an adjustment housing and is therefore not transferred to the drive element.
Torque on the drive side is transferred between the drive element and the load moment lock by means of elements which engage in each other with keyed connection. Since the position of the locking elements of the load moment lock changes through tolerance and wear as a result of high surface pressure, for the functional reliability of the known adjustment device it is necessary to incorporate a large amount of play so that rotational angle play is present between the interengaging elements conditional on the function without which a stepped transfer or change of direction of the torque on the drive side is not possible. A minimum rotational angle play must also therefore be present between the interengaging elements of the drive element and load moment lock in order to prevent any wear and to permit a certain elastic deformation.
However too much rotational angle play, particularly with a stepped transfer of the torque on the drive side, becomes unacceptably noticeable since the rotational angle play causes a correspondingly large idling path or idling stroke of the drive element. Moreover when reversing movement too much rotational angle play can lead to troublesome reverse play and to inaccurate handling.
The known adjustment device has a relatively larger reverse play in the brake unit conditioned by tolerances in the component parts. In order to restrict this it is necessary to carry out production accurately within a narrow tolerance band. The assembly of the individual component parts which are provided with low tolerances is expensive since the component parts which are to be connected together have to be positioned precisely relative to each other.
In order to minimize the rotational angle play between a drive element, an output element and a load moment lock and to ensure a secure force or torque transfer without any additional adjustment of the rotational angle play during assembly or re-adjustment of the rotational angle play after longer use, an adjustment device is proposed in the prior patent application 199 26 994.7 wherein between the drive element and the load moment lock or between the output element and the load moment lock there is a play compensating device which compensates the rotational angle play between the drive element, the output element and the load moment lock and with which the functionally conditioned rotational angle play between the drive element and the load moment lock or the load moment lock and the output element is automatically set and adjusted respectively.
To this end the load moment lock has in a cylindrical adjustment housing two locking elements arranged in pairs in two planes one above the other wherein the clamping faces through the action of the play compensating device bear against the adjustment housing with a predetermined pretension in that the play compensating device is arranged at least in part between the opposing expanding faces of the pairs of locking elements and forces the pairs of locking elements apart. The torque introduced on the output side increases the contact pressure of the clamping faces and thus of the pairs of locking elements against the adjustment housing.
The play compensating device furthermore serves to ensure the locking elements bear against the adjustment housing with the predetermined pretensioning force and to ensure an automatic re-adjustment which becomes necessary through wear on the component parts. It can consist for example of a wedge mounted between the expanding faces of the pairs of locking elements, whereby the wedge faces lie opposite the expanding faces of the pairs of locking elements and the wedge is guided displaceable with a wedge guide with keyed engagement in a slide guide of the drive element and is pretensioned radially by means of a spring so that the wedge faces rest against the expanding faces free of play. Alternatively the play compensating device can be formed as a cylindrical roller or ball or as an eccentric which is mounted rotatable between the expanding faces of the locking elements and is preferably designed as a stepped bolt.
An automatic adjustment of a minimum rotational angle play thereby takes place in both directions of rotation of the adjustment device taking into consideration the tolerances in the component parts and an automatic readjustment takes place to account for any wear on the component parts so that a minimum idling stroke is guaranteed during operation in both directions of rotation and high functional reliability is ensured for the adjustment device taking into account unavoidable wear. The manufacture of the individual component parts is thus considerably more cost-effective, assembling the adjustment device becomes easier and waste is restricted to a minimum.
The object of the present invention is to provide an adjustment device with optimum rotational angle play between a drive element, an output element and a load moment lock which during assembly requires no adjustment and even after longer use requires no re-adjustment of the rotational angle play and which can be constructed simply and in space-saving manner.
The solution according to the invention provides an adjustment device which ensures optimum rotational angle play between a drive element, an output element and a load moment lock and which requires neither adjustment during assembly nor re-adjustment of the rotational angle play even after longer use. Since the locking elements are only arranged in one plane of the load moment lock the adjustment device can be constructed very easily and in space-saving manner, although there is a change-over play when changing over from one adjustment direction into the other.
Preferably the play compensating device has wedge faces which bear against the output element and/or against the locking elements, and at least one spring which pretensions the play compensating device perpendicularly to the axis of the load moment lock in the sense of reducing the distance between the play compensating device, the output element and the locking elements.
Through the wedge faces in connection with the pretensioning force of the spring the locking element faces are constantly brought to bear against the cylindrical adjustment housing and thus optimum rotational angle play is guaranteed during setting up and even after longer term use of the adjustment device.
In order to avoid any resetting of the locking element surfaces which would break down the contact between the locking element surfaces and the cylindrical adjustment housing after operation of the adjustment device, the wedge faces include such an angle with the axis of symmetry of the load moment lock that the connection is self-locking between the play compensating device on the one hand and the output element and/or the locking elements on the other hand.
The wedge faces can be provided selectively between the play compensating device and the output element and/or between the play compensating device and the locking elements. In a first embodiment of the invention the wedge faces of the play compensating device bear against counter wedge faces of the output element and substantially flat faces of the play compensating device bear against the facing expanding faces of the locking elements or parts of the expanding faces.
The output element can have protrusions or curvatures formed symmetrical with the axis of symmetry of the load moment lock for spot or linear contact with substantially rectilinear or inclined surfaces of the play compensating device.
Correspondingly in a second embodiment of the invention the wedge faces of the play compensating device bear against the protrusions or curvatures of the output element and substantially flat surfaces of the play compensating device bear against the facing expanding faces of the locking elements or parts of the expanding faces.
In a third embodiment of the invention the wedge faces of the play compensating device bear against inclined expanding faces of the locking elements and the substantially rectilinear faces of the play compensating device bear against the protrusions or curvatures of the output element.
A further development of the solution according to the invention is characterised in that the drive element has claws which in the event of torque on the drive side after removal of the frictional contact between the locking elements and the adjustment housing engage with keyed connection in recesses of the output element and entrain the latter in the drive direction.
As an alternative to this the drive element can have recesses which in the event of torque on the drive side after removal of the frictional contact between the locking elements and the adjustment housing bear with keyed engagement against claws of the output element and entrain same in the drive direction.
With both variations after the frictional contact between the locking elements and adjustment housing has been lifted through the action of torque on the drive side a positive locking connection is produced between the drive element and the output element and thus a slip-free connection is established between the drive element and output element.